While I understand from that changelog that the modconf dependency was left out on purpose, shouldn't that change also require that all use of modconf be removed from the ppppoeconf script as a consequence?

Otherwise, the desire to satisfy the system (of full separation between main and universe) becomes an excuse to introduce bugs into packages.

Confirmed on a fresh Kubuntu installed yesterday. I've opened a topic about it on the French Ubuntu forum, and someone pointed me this bug report.

The idea from Mario Bonino (2007-09-08) to add modconf in the core installation, seems relevant indeed. Why was that bug report marked invalid ? A bug is really there, modconf is a dependency for pppoeconf, and this dependency is broken.